See the official prometheus-operator GitHub repo for an example ServiceMonitor YAML.
See the Prometheus Operator documentation for an example PodMonitor and an example Prometheus resource that refers to a PodMonitor.
A PrometheusRule contains the alerting and recording rules that you would usually place in a Prometheus rule file.
For a more fine-grained approach, the
ruleSelector field on a Prometheus resource can select which PrometheusRules should be loaded onto Prometheus, based on the labels attached to the PrometheusRules resources.
See the Prometheus Operator documentation for an example PrometheusRule.
See the Rancher docs page on Receivers for an example Alertmanager config.